Mixing enhancement mechanism of combined H2–Water jets in supersonic crossflows in a combustor with an expanded section

To obtain the mixing enhancement mechanism of H₂–Water combined jets in supersonic crossflows in a combustor with expanded section for rotating detonation ramjet, the flow field shape and spray structure were studied by experimental and numerical methods. The Eulerian–Lagrangian method was used to investigate the diffusion mechanism and H₂–Water interaction law of combined jets with different sequences. At the same time, high-speed photography and the schlieren technique were used to capture the flow field. The effects of jet pressure drop, orifice diameter, orifice spacing, incoming Mach number, and other parameters on the penetration depth of water jets were studied. The results of experiment and simulation show that using H₂–Water combined jets, the penetration depth of the jet spray can be greatly increased and the jet mixing effect can be significantly improved, which will contribute to the engine's ignition and stable combustion. In the case of pre-water/post-H₂, the penetration depth of the hydrogen jet is greater. In the case of pre-H₂/post-water, the hydrogen jet raises the water spray mainly by protecting the integrity of the water column.     

On the Enzymatic Formation of Metal Base Pairs with Thiolated and pKa-Perturbed Nucleotides

The formation of artificial metal base pairs is an alluring and versatile method for the functionalization of nucleic acids. Access to DNA functionalized with metal base pairs is granted mainly by solid-phase synthesis. An alternative, yet underexplored method, envisions the installation of metal base pairs through the polymerization of modified nucleoside triphosphates. Herein, we have explored the possibility of using thiolated and pK_a-perturbed nucleotides for the enzymatic construction of artificial metal base pairs. The thiolated nucleotides S2C, S6G, and S4T as well as the fluorinated analogue 5FU are readily incorporated opposite a templating S4T nucleotide through the guidance of metal cations. Multiple incorporation of the modified nucleotides along with polymerase bypass of the unnatural base pairs are also possible under certain conditions. The thiolated nucleotides S4T, S4T, S2C, and S6G were also shown to be compatible with the synthesis of modified, high molecular weight single-stranded (ss)DNA products through TdT-mediated tailing reactions. Thus, sulfur-substitution and pK_a perturbation represent alternative strategies for the design of modified nucleotides compatible with the enzymatic construction of metal base pairs.     

Evaluation of expanded gamut software solutions for spot color reproduction

Expanded gamut printing is an approach in color reproduction that expands the color gamut of conventional CMYK printing processes via the use of additional colorants, such as Orange, Green, and Violet inks. This study evaluates the ability of commercial color management software to create an accurate solution for an expanded gamut printing system. In this study, two printing processes were used, an Epson SureColor P9000 inkjet printer/proofer and an HP Indigo 7900 digital production press, both with 7-color expanded gamut ink sets. Software solutions from Alwan, CGS ORIS, ColorLogic, GMG Color, Heidelberg, and Kodak were evaluated. The systems were tested to see how well they could reproduce the colors in the entire PANTONE+ Solid Coated spot color library. It is shown that the solutions are able to reproduce 89% to 94% of the spot colors on the Epson P9000 inkjet printer and 77% to 87% of the library on the Indigo 7900, both to less than two CIEDE2000 (a typical tolerance in label and packaging work). The number of color patches in expanded gamut characterization test charts was noted, as this is still an area of proprietary, nonstandardized working practice. There are many different colorant combinations that can make the same color in expanded gamut printing. The ink build created by the different software solutions was studied, as it relates to press stability through appropriate choice of colorants. Pantone and Adobe provide everyday commercial tools for expanded color workflows. The study identified some issues with products from these companies that could confuse a less-skilled user in a busy production environment. The conclusion of the study is that expanded gamut solutions for spot color printing produce totally acceptable results for digital printing processes; expanded gamut printing is ready, here and now. The findings show that expanded gamut printing can replace cumbersome conventional spot color workflows creating considerable savings and advantages, especially for label and packaging printers.     

石蜡与石蜡/膨胀石墨熔化性能的实验研究

为改善相变储能过程中石蜡(PA)的熔化性能，向PA中添加少量膨胀石墨(EG)制备了4种配比的石蜡/膨胀石墨复合相变材料(PA-EG)。通过热物性分析筛选出合适配比的PA-EG，并对其和PA在水平管壳式相变储能单元中的熔化过程进行了实验研究。根据相变材料的温度场变化以及加权法计算得到的熔化分数变化，对比分析了添加EG前后PA的熔化性能，并探究了加热温度对相变材料熔化性能的影响。结果表明，PA-EG3的热导率比PA高了7倍，且两者的相变温度和潜热相差不大。PA-EG3熔化过程中的自然对流效应弱于PA，但是较高的热导率能够显著改善相变储能单元中下部的熔化，使得其整体熔化速度快于PA。当加热温度为80℃时，PA-EG3的熔化过程比PA缩短了78.16%。此外，降低加热温度会使PA和PA-EG3的完全熔化时间都显著增加，但相同条件下PA-EG3的增加幅度更小。     

带扩张段构型超声速气流中横向射流数值模拟

针对带扩张段构型的发动机燃烧室,采用欧拉-拉格朗日仿真方法研究喷注方式、喷孔参数及隔离段燃烧室构型的改变对于射流雾化效果的影响,用以更好地指导发动机设计.结果表明,在保证发动机总体流量不变的条件下,喷孔孔径减小或者喷孔总数量减少使得液气动量通量比增大,有利于同时增大单孔射流穿透深度以及液滴展向宽度.贫燃工况下如当量比为0.7条件下,射流流量减小,混合效果可能变差.而在发动机结构设计方面,隔离段到燃烧室的过渡设计不宜采用大转角,15°转角是相对较为理想的设计方案.采用小角度突扩构型设计比渐扩构型更容易找到相对好的点火位置.     

氯气压缩机扩能改造总结

介绍了氯气压缩机扩能改造方案,并结合实际,提出了改造过程中的注意事项.     

高效保温绝热涂料的研制

以丙苯乳液为主要成膜物质,膨胀珍珠岩、镁铝硅酸盐矿物、硅酸盐纤维增强剂为主要原料,制得了高效保温绝热涂料,其导热系数0.0594W/(m.K)。     

矿渣粉磨用多孔膨胀珍珠岩复合助磨剂的研究

以多孔膨胀珍珠岩为载体,三乙醇胺、乙二醇、十二烷基苯磺酸钠和三聚磷酸钠为助磨剂复配了一种矿渣粉磨用多孔膨胀珍珠岩复合助磨剂,研究它对矿渣的助磨效果.将不同加入量的复合助磨剂在相同的粉磨条件下与矿渣共磨20～95 min,测定各矿渣粉的比表面积和45 μm筛余量,并与空白样品对比;然后对粉磨65 min所得的矿渣粉用图像分析仪和扫描电镜进行了形貌分析,用激光粒度分布仪进行了粒度分析;同时又研究了此复合助磨剂对矿渣-水泥体系标准稠度用水量、凝结时间、胶砂强度等各项性能的影响.结果表明:本试验的复合助磨剂的助磨效果好,对矿渣水泥的性能无损害且能够提高胶砂强度;矿渣的小磨试验中此复合助磨剂的最佳用量为矿渣质量的0.04%～0.08%,粉磨时间应大于35 min后矿渣粉中10～20 μm颗粒的含量相对空白明显增加.     

Design and construction of expanded polystyrene embankments Practical design methods as used in the United Kingdom

This paper covers the history of the use of expanded polystyrene ( ) in light weight fill for road embankments. UK design requirements and physical properties of the foam are covered together with two case studies.     

夯扩桩的设计应用研究

夯扩桩作为一种经济桩型,即使在今后相当长一段时间内仍具使用价值,但存在该用夯扩桩时工程技术人员却怕用的现象。因此,本文根据作者对大量工程设计与施工实践的积累总结,就夯扩桩的正确设计方法进行了一些分析探讨。强调了夯扩桩设计时应着重注意的一些问题,并针对一些观点提出了见解及分析,以期利于工程设计实践。